diff --git a/src/class/dfu/dfu_device.c b/src/class/dfu/dfu_device.c
index 8d859d2ee..aa5891ca9 100644
--- a/src/class/dfu/dfu_device.c
+++ b/src/class/dfu/dfu_device.c
@@ -167,6 +167,8 @@ uint16_t dfu_moded_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc,
   uint8_t alt_count = 0;
 
   uint16_t drv_len = 0;
+  TU_VERIFY(itf_desc->bInterfaceSubClass == TUD_DFU_APP_SUBCLASS && itf_desc->bInterfaceProtocol == DFU_PROTOCOL_DFU, 0);
+
   while(itf_desc->bInterfaceSubClass == TUD_DFU_APP_SUBCLASS && itf_desc->bInterfaceProtocol == DFU_PROTOCOL_DFU)
   {
     TU_ASSERT(max_len > drv_len, 0);